This invention relates to a variable valve actuating apparatus for an internal combustion engine which is configured to variably control an operation characteristic of an engine valve which is an intake valve and/or an exhaust valve of the internal combustion engine.
U.S. Patent Application Publication No. 2010/212617 A1 (corresponding to Japanese Patent Application Publication No. 2010-196486) discloses a conventional variable valve actuating apparatus.
The above-described variable valve actuating apparatus includes two intake valves in each cylinder; an inner cam shaft integrally provided with an inner cam provided on an outer circumference of the inner cam shaft, and arranged to drive one of the intake valves; and an outer cam shaft disposed on an outer circumference of the inner cam shaft to be relatively rotated (relative to the inner cam shaft), and integrally provided with an outer cam provided on an outer circumference of the outer cam shaft, and arranged to drive the other of the intake valves. At an end portion of the inner cam shaft and an end portion of the outer cam shaft, there are integrally provided, respectively, two vane-type hydraulic actuators which are arranged in series (with each other) in an axial direction.
The two hydraulic actuators are arranged to relatively rotate the inner cam shaft and the outer cam shaft by the supplied hydraulic pressure, and thereby to control the operation angle of the intake valve. Moreover, the two hydraulic pressure actuators are arranged to relatively rotate the inner cam shaft and the outer cam shaft relative to (with respect to) the crank shaft, and thereby to control opening/closing timing of each intake valve.